Insurance Replaced Rear End Now Loosing Gas Mileage ?

[Glenn]

Just got my truck back after having a body shop an Allstate Insurance pro shop replace the rear end after a accident and my mpg's are messed up getting about 50 miles less to a tank full now.

I don't know much about rear ends I'm thinking they had to of put the wrong rear end in.

It's a pretty old truck a 93 2wd Ranger STX so i guess they just tracked down a old rear end at junk yard.

Since its a Allstate pro shop they warranty it for life actually this is the second rear end they put in the first had some problems axle seals leaking and some other problems and they said it needed to be replaced.

Is there a way to confirm if its the wrong rear end without pulling it apart ?

Looking for options on how i should handle this.

 

[Shran]

I'd find out what gears you had in the first and compare them to the gears you have now...if you ended up with lower gears your gas mileage might go down due to the difference in RPM.

Since it's a 2WD they may have just figured you wouldn't notice, but hopefully that's not the case.

 

[MAKG]

Simplest is to calibrate the odometer. Second simplest is to measure the fuel you ACTUALLY use. Perhaps a tank isn't what it used to be.

 

[fastpakr]

To start with, measuring fuel efficiency by the tank is a complete waste of time. Distance travelled / fuel USED (not tank size) is the accurate measurement.

I'd be shocked if any reasonable change in gearing could make a 50 mile difference in a single tank.

 

[Shran]

I dunno man...something to check anyway I guess.. I get about 22MPG highway with 3.45 gears in one truck (manual trans) and 17MPG with 3.73 gears in the other, but it's an auto. Both have 2.9's. Granted the difference is probably due to the trans more so than the gears.

 

[Glenn]

I really don't know much about how to accurately measure fuel efficiency.
All I do know is that when i bought my truck new in 93 I filled the tank and I got between 240 to 260 miles to a tank full and in the 15 years I owned it I always consistently gets me the same 240 to 260 no matter what unless i do straight highway driving . Now after the rear end swap I'm seeing 200 to 210
I just know it has to be that rear end.

To start with, measuring fuel efficiency by the tank is a complete waste of time. Distance travelled / fuel USED (not tank size) is the accurate measurement.

I'd be shocked if any reasonable change in gearing could make a 50 mile difference in a single tank.

 

[Hahnsb2]

You probably ended up with higher gears, thus throwing off your speedo/odometer as well as changing your fuel millage.

 

[hitech_hick]

You probably ended up with higher gears, thus throwing off your speedo/odometer as well as changing your fuel millage.

Yeah, I would compare the current axle ratio to the ratio on the door tag, if there is a discrepancy, make them fix it.


hick

 

[kunar]

You probably ended up with higher gears, thus throwing off your speedo/odometer as well as changing your fuel millage.

DING DING DING!!! we have a winner!!

if the gears are different, your speedometer will be off. if thats the case, your odometer will be wrong as well. you may be getting the same mileage and not even realize it.

 

[Glenn]

I checked the speedometer odometer for my speed against one of those police radar speeding readers that that police put out on the street to tell you if your speeding and I it seems to be right on

DING DING DING!!! we have a winner!!

if the gears are different, your speedometer will be off. if thats the case, your odometer will be wrong as well. you may be getting the same mileage and not even realize it.

 

[flyingbrick]

Assuming it was a good shop they would have corrected the speedometer before letting the truck go.

If the truck seems to speed up slower/ faster the gearing could be different.

 

[AllanD]

For whatever it's worth.

2.9 manual transmission trucks get progressively better mileage as you
switch from 3.45, to 3.73 and even to 4.10's if you stick to "reasonable"
tire sizes.

The thing is to drive the same speed with the lower gears requires less
throttle opening and that seems to be the most important thing with the 2.9.

But unless your speedo/odo is calibrated correctly you'll have no idea what you are getting for mileage.

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[4x4junkie]

I still say check the ratio.

It's pretty well known (here anyway) that in most cases taller ratios actually use MORE fuel than shorter ratios on Rangers. If they put a 3.08 in there and you had 3.55 before, that could very well be the reason.